An example of conventional chip resistors is disclosed in JP-A 2002-57009. FIG. 26 of the present application is a sketch of the resistor disclosed in the gazette (The entire resistor is indicated by a reference symbol B). The chip resistor B includes a rectangular resistive element 90 made of metal, and a pair of electrodes 91 formed on a lower surface of the resistive element 90. The two electrodes 91 are spaced from each other by a distance s5. Each electrode 91 has a solder layer 92 formed thereon.
The chip resistor B is manufactured by means of a method shown in FIGS. 27A-27E. First, two metal plates 94, 95 are prepared (FIG. 27A), and the metal plate 95 is bonded to a lower surface of the metal plate 94 (FIG. 27B). The upper metal plate 94 has a relatively larger electric resistance than the lower metal plate 95. The lower metal plate 95 is made of copper for example, and has a smaller electric resistance. Next, part of the lower metal plate 95 is ground off by machining, to form a gap 93 (FIG. 27C). On the remaining portion of the metal plate
95 is formed a solder layer 96 (FIG. 27D). Finally, the metal plate 94 (and the related members 95, 96) are cut into chip resistors B.
According to the conventional method of manufacture described above, the chip resistor B has its electrodes 91 (FIG. 26) formed by mechanical grinding of the lower metal plate 95 (FIGS. 27B, 27C). As will be understood easily, in order for the device B to function properly as a resistor, it is not preferable that part of the electrically conductive metal plate 95 is left between the two electrodes 91. Therefore, the depth of grinding into the metal plate 95 must be at least the same as the thickness of the metal plate 95. However, it is not easy in general to make such an operational setting accurately.
If the grinding depth is greater than the thickness of the metal plate 95, the upper metal plate 94 is ground partially, which alters the resistance value. Further, in mechanical grinding, it is difficult to achieve an exact dimension for the distance s5 between the two electrodes 91, and therefore a certain level of error is unavoidable.
For these reasons, a trimming operation is performed to the conventional chip resistor B in order to make adjustment to the resistance value. However, performing the trimming to all of the resistors which are manufactured leads to increased cost of manufacture.